Valuable Gem Bought at Second Hand Store

‘The price of natural pearls has surged dramatically over the past few years,’ says Benjamin. ‘Modest, natural saltwater pearls can be worth £10,000 while a Twenties two-row pearl necklace can fetch well above £25,000.’ Gems are attracting new buyers.

‘Imperial topaz of good quality is rare and making high prices, but so are other coloured stones because the uncertainty of the financial markets has lead people to consider other avenues for investment,’ says Dr Ogden.

My daughter, Imogen, four, loved to wear my pretty brooch on the bodice of her Disney Princess dress or tied with a ribbon in her hair. The pretty orangey-pink stone, surrounded by faux diamonds, sparkled and the gold-coloured setting almost looked real.

I had bought it from a junk shop for £20, so I knew it was just flashy old tat. Or so I thought.In a week’s time, this bauble will go on sale at Bonhams fine jewellery sale in London — with a conservative guide price of £3,000 to £4,000. It could fetch much, much more.

It has travelled to New York and Hong Kong for exclusive viewings by potential buyers and bids are expected from all over the world. My humble knick-knack has turned out to be a magnificent example of early 19th century jewellery, possibly part of a tiara or necklace that may have graced the neck of a Russian Czarina.

What scares me is that Imogen’s insistence on wearing it on the most inappropriate occasions — to the post office, at the school play — means she could easily have lost it countless times. Worse, I probably wouldn’t have noticed.

‘People don’t realize they have a treasure among their possessions,’ says jewellery historian John Benjamin, who regularly appears on The Antiques Roadshow. ‘But somewhere in a drawer is a trinket they inherited that may be worth a fortune.’